Modelling rubber dynamic stiffness for numerical predictions of the effects of temperature and speed on the vibration of a railway vehicle car body

Abstract

Using a viscoelastic model containing a temperature spectrum and a friction model, a nonlinear model of rubber elements has been developed and verified. It takes into account the correlation between temperature, vibration frequency, and vibration amplitude, its parameters are identified by conducting static tests and dynamic mechanical thermal analysis. Then, it is used in a dynamic model for high-speed railway vehicles containing suspended under-chassis equipment (UCE). The coupling between the vibrations of the car body and UCE that considers the temperature-dependent characteristics of the rubber elements is studied, and trends for the modal vibrational energy of the UCE and car body are identified. The results indicate that the decrease in the ambient temperature significantly increases the dynamic stiffness of the rubber elements, which impairs their function. It also generates more intense UCE vibrations and increases the vibrational energy of the low-frequency (first-order vertical bending and diamond-shaped deformation) modes of the car body, thus degrading the ride quality assessed via the Sperling index. At extremely high ambient temperature (around 40 °C), the dynamic stiffness and damping coefficient of rubber elements decreases, thus weakening the damping effect and increasing the vibration amplitudes of the car body and UCE. Considering the dynamic stiffness of the rubber elements at 20 °C as a reference, the dispersion of their dynamic stiffness should be maintained within the range [−20%, 50%] at temperatures between −30 and 40 °C to ensure good ride quality of the vehicle at running speeds above 300 km/h.